3,546 research outputs found

    Quantum percolation in quantum spin Hall antidot systems

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    We study the influences of antidot-induced bound states on transport properties of two- dimensional quantum spin Hall insulators. The bound statesare found able to induce quantum percolation in the originally insulating bulk. At some critical antidot densities, the quantum spin Hall phase can be completely destroyed due to the maximum quantum percolation. For systems with periodic boundaries, the maximum quantum percolationbetween the bound states creates intermediate extended states in the bulk which is originally gapped and insulating. The antidot in- duced bound states plays the same role as the magnetic field inthe quantum Hall effect, both makes electrons go into cyclotron motions. We also draw an analogy between the quantum percolation phenomena in this system and that in the network models of quantum Hall effect

    Surface and Edge States in Topological Semi-metals

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    We study the topologically non-trivial semi-metals by means of the 6-band Kane model. Existence of surface states is explicitly demonstrated by calculating the LDOS on the material surface. In the strain free condition, surface states are divided into two parts in the energy spectrum, one part is in the direct gap, the other part including the crossing point of surface state Dirac cone is submerged in the valence band. We also show how uni-axial strain induces an insulating band gap and raises the crossing point from the valence band into the band gap, making the system a true topological insulator. We predict existence of helical edge states and spin Hall effect in the thin film topological semi-metals, which could be tested with future experiment. Disorder is found to significantly enhance the spin Hall effect in the valence band of the thin films

    Recent advances in femtosecond laser-assisted cataract surgery

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    Perfect vision and fewer complications is our goal in cataract surgery, femtosecond laser-assisted cataract surgery hold the promise. Applications of femtosecond laser technology for capsulotomy, nuclear fragmentation and corneal incision in cataract surgery bring a new level of accuracy, reproducibility and predictability over the current cataract surgery. The femtosecond laser produces capsulotomies that are more precise, accurate, reproducible, and stronger than those created with the conventional manual technique, and further helps maintain proper positioning of the IOL. Femtosecond laser in nuclear fragmentation lead to a lower effective phacoemulsification time, and the corneal incision is more stable. But currently there are some complications and a clear learning curve associated with the use of femtosecond lasers for cataract surgery. The long-term safety and visual outcomes still need further investigation

    Fashion and Sustainability: Consumption and Shared Responsibility

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    Indulgence in fashion has been indispensable in modern societies, as it is a crucial device for self-image and identity construction. With the advanced technology and globalization of production, the fashion industry has skewed towards fast fashion, making the latest trends available to mass consumers at affordable prices. This research aims to examine how Chinese consumers perceive sustainable consumption in the context of fashion. We endeavor to explore the factors that influence the engagement of sustainable consumption. This study aims not to argue whether sustainable fashion should mobilize or replace the current fashion system but to provide evidence on consumers\u27 perception of sustainability and explore potential factors influencing sustainable behavior

    An improved algorithm for Generalized \v{C}ech complex construction

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    In this paper, we present an algorithm that computes the generalized \v{C}ech complex for a finite set of disks where each may have a different radius in 2D space. An extension of this algorithm is also proposed for a set of balls in 3D space with different radius. To compute a kk-simplex, we leverage the computation performed in the round of (k−1)(k-1)-simplices such that we can reduce the number of potential candidates to verify to improve the efficiency. An efficient verification method is proposed to confirm if a kk-simplex can be constructed on the basis of the (k−1)(k-1)-simplices. We demonstrate the performance with a comparison to some closely related algorithms
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